This invention relates to a method and means for providing a sterile transfer of fluids between two containers.
The problem of the sterile transfer of fluids arises in a number of different areas, however the most immediate need seems to be in the area of blood handling. Since blood contains several major different components, each serving a unique function, the use of whole blood for transfusion has become unnecessary in many cases. Instead required components can be removed, allowing the balance of the blood to be employed elsewhere. Thus, blood component therapy has helped to ease the blood shortage somewhat, at a time of rapidly increasing demand.
The red blood cell fraction represents the most widely used component of blood. About 70% of all blood transfusions call for red blood cells. Freezing methods allow red cells to be stored for many months without loss of quality, however, none of the present methods for processing frozen-thawed blood can guarantee sterility. A long-standing FDA ruling places a 24-hour outdating limit on blood once it has been thawed. The present ruling has evolved from an earlier FDA policy, still in effect, which places the same limit on blood or any blood component, once its sterility can no longer be assured. For some blood fractionation applications, the 24-hour outdate problem can be sidestepped by employing blood collection bags with one or more attached satellite bags. To remove plasma aseptically from a collection bag, for example, a bag of blood with an empty satellite bag attached is centrifuged and the supernatant fluid (plasma) can then be expressed into the satellite bag. The common tubing connecting the 2 bags is then sealed and detached, yielding a unit of "sterile" packed cells and the unit of "sterile" plasma.
Satellite bags supply however, only a partial answer to the sterility problem. The collection bags are cumbersome and costly. Furthermore, they solve neither the sterile entry problems associated with the cell washing, nor the sterility problems associated with frozen blood processing. Accordingly, there is still a need for a scheme for removal or addition of fluid which has assured sterility, without any of the prior art problems such as the satellite bag briefly described above.